1. Technical Field
Embodiments of the present disclosure are directed to leadframe strips and leadless packages, as well as methods of manufacturing leadframe strips and assembling leadless packages.
2. Description of the Related Art
Leadless (or no lead) packages are often utilized in applications in which small sized packages are desired. In general, flat leadless packages provide a near chip scale encapsulated package that includes a planar leadframe. Lands located on a bottom surface of the package and, in many cases, side surfaces of the package provide electrical connection to a board, such as a printed circuit board (PCB).
Leadless packages are typically formed from a leadframe strip of conductive material that includes a plurality of spaced apart die pads and leads that are located between adjacent die pads. The leads and die pads are typically connected together by tie bars. Electrical devices, such as integrated circuits, are secured to an upper surface of each die pad.
After the electrical devices have been electrically coupled to one or more leads, such as by wire bond or solder ball techniques, encapsulation material is provided over the upper surface of the leadframe strip and covers the electrical device and the conductive wires or solder balls. The leads of the leadframe strip and the encapsulation material are then cut through, such as by dicing, to form individual packages.
Cutting through the leadframe strip and the encapsulation material is typically done in a single dicing step. In general, the dicing step involves a saw blade that cuts through the encapsulation material and the leadframe strip. The encapsulation material and the leadframe strip are distinct materials and have different material properties. In an ideal environment, the differing materials may favor different rotational speeds and/or materials for the saw blade.
By performing the cutting in a single dicing step, the sawing process can cause saw burrs that extend beyond a bottom surface of the leads. These saw burrs can cause attachment issues during board attach. For instance, the saw burrs can prevent the packages from lying substantially flat on the surface of the board.
Moreover, friction between the saw blade and the lead can cause the leads to smear along its outer surface and in some cases into the encapsulation material. If the lead smear is significant, it can create shorting between adjacent leads.